In traditional concept walkways each pallet is attached to the traction chain such that the pitch of the pallets must be a whole number of chain pitches.
In addition, the excessive pitch of the pallet forces having very high transition radii in the curves of the inclined walkways, in short making the walkway too long. When the pitch of the pallet is very large, the polygon which it makes does not allow reducing the transition circumference as accurately, therefore in one rotation direction gaps are opened between the pallets, unacceptable by the standard, and in the other rotation direction interferences occur which do not allow the rotation between pallets.
Other types of walkways with pallets have been proposed in order to solve these problems as those described in patents JP08198561A2, U.S. Pat. No. 4,244,457, U.S. Pat. No. 6,607,064, U.S. Pat. No. 7,063,202 and U.S. Pat. No. 3,247,947.
U.S. Pat. No. 4,244,457 and U.S. Pat. No. 6,607,064 propose concepts in which each pallet is hinged in several parts, allowing the transition radii in the paths of the pallets to be smaller and reducing the total size of the walkway. However they continue maintaining the pallet chain which is traditionally used to carry out the transition on the walkway, the primitive diameter of which is what marks the size of the heads. This involves an extra cost and a relatively large size of the heads.
U.S. Pat. No. 7,063,202 proposes a support between pallets in which the pallet is supported, on one hand on its rollers and on the other hand it is supported on the next pallet, distributing the load between the adjacent pallets. An effective attachment between pallets is not carried out because the traction is carried out with a belt. Therefore at the time of supporting a pallet on the next pallet, noises can occur. In the return branch of the pallets, the support between pallets is not carried out due to gravity, therefore the position of the pallets is defined by the support rollers and by the binding to the traction belt, forming a situation which is not very stable, taking into account that the belt is an elastic element.
These three types of walkways as well as the traditional traction concept have the drawback of the high number of components needed, increasing both the cost and time necessary for their assembly.
In the case of patent JP08198561A2 a walkway is proposed in which the pallets allow reducing the height thereof, but said pallets are not attached to one another, such that they can only be moved by thrust and not by traction. This would generate compression problems for the walkway, with the possible opening of gaps in certain areas. On the other hand, the overturning is carried out such that it does not allow the pallets to be hinged to one another. It also makes it necessary to install four rollers in each pallet as well as the guiding and counter-guiding along the entire run of the walkway.
In U.S. Pat. No. 3,247,947 the pallets are attached to one another by means of a hinge needing lubrication in order to prevent excessive wear between both surfaces, causing the appearance of lubricant both in visible areas of the pallet and in the adjacent areas. In addition, this patent proposes grooves ending in a rounded manner with the center in the hinge between pallets in order to prevent the interference between adjacent pallets. This solution causes sharp concave shapes which can be dangerous for the users.